RFR: 8282944: GHA: Add Alpine Linux x86_64 pre-integration check [v12]

[Magnus Ihse Bursie]

On Mon, 19 Aug 2024 15:33:07 GMT, George Adams <gdams at openjdk.org> wrote:

>> Adds Alpine build CI job to the GitHub actions matrix. Currently this only builds hotspot. I can add tests too if people think that would be useful but for now I've left it as just build.
>
> George Adams has updated the pull request incrementally with one additional commit since the last revision:
> 
>   move EXCLUDED_PLATFORMS definition to the top of the job

Marked as reviewed by ihse (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/20577#pullrequestreview-2248188407